Brain Pathology Case of the Month - February 2001

Spinal SAH was an unexpected postmortem finding in this elderly man. In the past, he had been investigated for 20 years of (non-familial) progressive ataxia, receiving a diagnosis of sporadic cerebellar degeneration. His neurodegenerative disorder had prompted a neuropathological referral, a diagnosis of idiopathic late-onset cerebellar ataxia being made.

His terminal illness had been characterised by renal failure and laboratory evidence of an immunogenic disorder. Spinal SAH usually presents with intense back pain and spinal rigidity, to be followed by the consequences of damage to the spinal cord and nerve roots. This presentation was not apparent, but may have been obscured by other clinical problems.

Histological examination revealed non-granulomatous inflammation of arcuate and interlobular arteries in the kidney and small arteries and venules in the spinal leptomeninges. A diagnosis of microscopic polyangiitis (MPA) is consistent with these findings and the immunology results (1, 2). Wegener's granulomatosis (WG), another small vessel vasculitis, and polyarteritis nodosa (PAN) comprise the differential diagnosis. According to modern classifications (1), PAN is excluded on the basis that it affects predominantly medium-sized vessels and not venules, and is rarely associated with ANCA. WG may appear histologically similar to MPA, and both may affect the respiratory system. However, WG usually displays granulomatous inflammation, and is associated much more with cANCA than pANCA (1, 3).

Spinal SAH is rare (4), and is usually produced by rupture of an arteriovenous malformation. It is occasionally associated with trauma, or bleeding from an intraspinal tumour such as ependymoma. Clinicopathological correlation has implicated polyarteritis nodosa (PAN) as a cause of spinal SAH in a few patients (5, 6), and there have been isolated reports of spinal SAH in patients with systemic lupus erythematosus (7), rheumatoid arthritis (8), and Sjögren's syndrome (9). A spinal subdural haematoma due to granulomatous angiitis of the nervous system in a patient with non-Hodgkin's lymphoma has also been reported (10). In cases of spinal SAH associated with vasculitis, breakdown of the inflamed vessel wall is assumed to be the cause of hemorrhage.

The authors acknowledge support from Dr. David Jarrett and Dr. Margaret Jeffrey of Queen Alexandra Hospital, Portsmouth.